In the past, various types of dual thermostats have been employed for automatically controlling the operating modes of both a cooling system and a heating system adapted to condition, within a predetermined temperature range, the temperature of a space to which such thermostats were subjected, and of course, in some instances a heat pump was utilized in conjunction with such cooling and heating systems.
Various mechanical schemes have been employed in the past dual thermostats to adjust the positions of the spiral bimetals for effecting control of the cooling and heating systems throughout the aforementioned predetermined temperature range. In one such past dual thermostat, the spiral bimetals were mounted to a pair of posts or axles rotatably supported in a housing of the dual thermostat, and such posts were drivenly connected to a pair of levers having an adjusting member threadedly interconnected therebetween. Adjustment movement of the adjusting member threadedly drove the levers and posts until the desired adjusted position was attained for the spiral bimetals wherein such spiral bimetals were responsive at certain temperatures in the predetermined temperature range to effect the actuation of the switch means pairs respectively carried thereby. Of course, a temperature selecting knob was employed to manually move the adjusting member and urge the spiral bimetals toward positions so as to operate at the set point temperature selected upon the manual movement of the temperature selecting knob.
In another of the past thermostats, the spiral bimetals carrying the switch means pairs were also mounted to the rotatable posts, and the levers were drivingly connected with the posts generally in the same manner as discussed above; however, the levers were provided with a pair of abutments extending toward each other. When one of the levers was manually moved toward a set point position for adjusting the position of its associated spiral bimetal so as to control within the predetermined temperature range the operating mode of the cooling system or heating system associated therewith, the abutment on the one lever engaged the abutment on the other of the levers so as to drive it and its associated bimetal toward a position so that the such associated bimetal would not effect the trip point actuation of the switch means pairs wherein the one of the cooling system and heating system associated therewith was rendered, in effect, nonoperative or disabled.